Make entire menu transparent

Is it possible to have the entire top menu transparent on page load? I am not very experienced in code and feel like this may have to do with z-index but I am not sure.

Here is my site: https://www.diveemerald.com/

And here is a similar look I am trying to achieve (a different theme on a test site): https://www.greaterchattanoogaphotography.com/beachtest/

I am not using the built in slider, I’m using meta slider instead since I just want an image and no link to posts. I’d like the slider to extend all the way to the top of the screen and have the menu appear on top of it. I’ve tried removing backgrounds on all the elements up there with custom css, but there still seems to be something covering the slider even though it is positioned higher.

Any ideas?